The appetite is partly under control of the will and may be trained. It is more or less capricious and may be satisfied with little, or it may demand large amounts of food. Grief or worry will destroy it, as will foul air, and overfatigue. A voracious appetite may be due to an irritation of the nerves of the stomach or to a disturbance of digestion of one kind or another. This is shown by the fact that sometimes those with abnormal appetites are thin and undernourished because of non-digestion of the food. If the food is eaten slowly and well chewed, the desire for too great an amount will be lessened. The food will also be better digested. The chalk-eating, clay-eating, salt-eating habits are well known. The desire is largely mental and may be treated by substituting healthful thoughts for morbid longings, and changing the monotonous or restricted diet for one more liberal. If the appetite is lacking because of physical exhaustion, it is unwise to eat, because the digestive organs are tired, and to load a tired stomach with food, still further weakens it and results in indigestion. The better plan is to drink two glasses of cold water and lie down for an hour. Lack of appetite and the taste for highly seasoned food may come from a monotonous diet or one that does not contain sufficient coarse food or sufficient water to stimulate peristalsis; the result is stagnation and constipation, with the disorders that follow in its train. The monotonous diet, from its effect on the mind, results in lack of desire for food. Both the condition and the appetite are often stimulated and changed by a greater variety in the kinds of food. Care should be taken not to form the habit of using stimulants too freely, particularly with children. Condiments and stimulants, used to make the food “appetizing,” unduly stimulate the nerves, and pervert the natural taste, and foods containing their natural amount of spices or extractives no longer tempt one. Those whose nerves are highly keyed, form the habit of seasoning the food too highly. This undue stimulation calls for more food at the time of eating than a normal appetite would demand. The taste being cultivated for the stimulant, the habit of eating too much food is formed. A wise provision of Nature makes the system, in a normal condition, its own regulator, protesting against food when it has not assimilated or eliminated that consumed. One should learn to obey such protests and cut down the quantity when Nature calls “enough,” and exercise to eliminate waste, thus creating a better assimilation. Nature does not call for more food until she has eliminated the excess of waste. There are exceptions, however. Some phases of indigestion cause a gnawing sensation in the stomach which is often mistaken for a desire for food. This is not a normal appetite. Water will usually relieve it.